How to Tell a Dolphin From a Porpoise

You may have thought that the words "dolphin" and "porpoise" refer to the same animal, but actually there are differences between the two mammals. Even though they look very similar, dolphins and porpoises have several clear distinctions. Read on to learn how to tell a dolphin from a porpoise.

Instructions

1. Place the animal into the proper scientific classification. While dolphins and porpoises belong to the same order (Cetacea) and suborder (Odontoceti) they are in different families. Dolphins are in the family Delphinidae and porpoises are in the Phocoenidae family.

2. Measure the length of the cetacean. If the animal does not exceed seven feet in length as an adult, it is a porpoise. If the mammal grows up to 10 feet long, it is a dolphin. Porpoises also appear physically "chubbier" than the long, sleek dolphins.

3. Examine the animal's dorsal fin. If its back fin is triangular, it is a porpoise. If the fin looks like a wave, it is a dolphin.

4. Look at the mammal's mouth. If it has a rostrum (beak), it is a dolphin. Porpoises do not have rostrums. A porpoise's teeth are spade-shaped, but the teeth of a dolphin are cone-shaped.

5. Judge the longevity of the cetacean. If the animal can live 50 years or longer, it is a dolphin. If it only lives around 15 to 18 years, it is a porpoise.

6. Determine how social the animal is with other species. Dolphins are much friendlier than porpoises. They "flirt" with boats, swim in large groups and are seen in marine shows. They also use whistling to communicate with other dolphins underwater. Porpoises rarely show themselves above the water and do not use whistling as communication.